First you need to find on page 9 of this topic, my post with a link to the image of the usb drive and a link to the post with the image of DSM (.pat file)
Then you need to write the image to a USB flash drive using dd.
Next you need to modify the file named vender on a flash drive to set the mac-address of your server.
Then boot from usb, install DSM as usual.
Additionally you may write modules from https://docs.google.com/file/d/0B5tpWhE ... sp=sharing to your DSM (/lib/modules)
No, I did not build this module, as I do not have a controller for testing.
You may build new kernel by yourself from my github repo, just enable CONFIG_MEGARAID_SAS in kernel config for your controller.
Of course, if you know this procedure.
You may try to build qemu.

Hello again!
https://docs.google.com/file/d/0B5tpWhE ... sp=sharing - synoboot image, that curently running on my hardware
.pat files can be taken from here: viewtopic.php?f=2&t=555
There is same bugs with usb-hid, like in previous build (dsm 4.1), so usb ups support stil broken .